1. Field of the Invention
The present invention relates to a spaced sheathing roofing system and method of installing same, and particularly to a spaced sheathing roofing system providing enhanced insulation and waterproofing properties.
2. Description of the Related Art
There are two basic techniques of pitched roof construction. The most common technique involves nailing sheets of wood, typically plywood or decking material, to truss rafters to form a pitched roof deck. The pitched roof deck is overlaid with a roof substrate made of a waterproofing material. Typically, the waterproofing material forming the roof substrate is a roll goods membrane or underlayment comprising one or more plies of asphaltic or modified bitumen impregnated felt attached to the pitched roof deck by nails and/or adhesive. Felt is generally made of wood pulp and rag or of asbestos, polyester or glass fibers. Roof cladding provides the outer roof covering on the pitched roof system. One example of roof cladding is a roof tile. Roof tiles are extremely durable and provide significant aesthetic and decorative effects to the structures to which they are applied. Roof claddings may be made of cementitious materials and also brick, stone, clay, plastic, wood, metal, rubber or bituminous materials.
Roof cladding is secured primarily to the pitched roof system with mechanical fasteners. Nails are the primary mechanical fasteners for securing roof cladding to a wood deck. Roof tiles are commonly secured with a nail inserted through a hole in the roof tile and driven through the roof substrate and wood deck. Mortar is sometimes used in conjunction with nails to provide holding force of the roof tile to the roof deck.
The use of a plural component adhesive for attaching roof cladding to the exterior surface of a pitched roof deck is disclosed in assignee's U.S. Pat. No. 5,362,342. The '342 patent discloses a method of bonding tile roof components to the roof substrate utilizing polyurethane foam as the bonding medium. The method includes the step of applying under low pressure a stream of two component foamable liquid polyurethane on a prepared roof substrate. The foamable liquid polyurethane has a density preferably in the range of one and one-half to two pounds per cubic foot and a reactivity period in the range of one and one-half to four minutes. The foamable liquid polyurethane is preferably applied at a rate in the range of two to three pounds per minute. The tile roof component is placed into contact with the foamable liquid polyurethane during the reactivity period of the foamable liquid polyurethane.
The second technique of pitched roof construction is referred to as a spaced sheathing roof assembly. This technique has more limited applications and is used in certain geographic locations. In the spaced sheathing technique, batten strips, generally two to six inches wide, are affixed perpendicularly to the truss rafters and spaced according to the dimension of the selected roof cladding. The roof cladding, typically concrete or clay roof tiles, are allowed to be loose lain on the batten strips. Alternatively, the roof tiles may be occasionally nailed to the batten strips. When desired, an optional underlayment is positioned above the truss rafters and below the batten strips. Ferrous roof panels may be installed, using a limited number of mechanical fasteners on similarly arranged batten strips. Nonferrous cladding such as wood shingles may be installed and nailed to the batten strips in the same manner.
In the conventional spaced sheathing roof assembly, each of these roof coverings offers its own economic and aesthetic advantage, but all have similar shortcomings. The shortcomings of the spaced sheathing roof assembly are that it provides little or no insulation value to the structure, little protection from leaking during high wind and unexpected high rainfall events as well as, structural movement or racking of the roof assembly during high wind events and seismic disturbances.
It is desirable to have a spaced sheathing roof system that provides insulative value to the structure, significant leak protection and resistance to structural movement or racking of the roof assembly. It is also desirable to have an adhesive attachment assembly and method for concrete, slay and slate roof tiles and ferrous and non-ferrous roof panels for spaced sheathing applications.
Furthermore, it is desirable that the method of installation be simple, non-labor intensive, economical and not require excessive installation time. Furthermore, the roofing system should withstand the long-term effects of temperature and climatic variations experienced by the roofing system under normal circumstances